Measure the length of rod that will be needed for your application with a tape measure. Be sure to include any portion of the rod that might be driven into the ground for something like fence posts.
Mark the necessary length on the rod with the pencil.
Place the rod in the vise to ensure a stable work platform. Block the teeth of the vise with scrap wood to protect the rod, if necessary.
Use a hacksaw to cut the rod according to the mark. Maintain a smooth even stroke to allow the saw teeth to effectively cut the material.
Remove any burs left behind from the saw with a metal file.
Spray the freshly cut end of the rod with the cold galvanizing spray paint. Be sure to the entire end surface and continue up the rod 2-3 inches to ensure adequate coverage.